2014 AMC 12A Problem 4

Problem 4 of 25EasierAlgebra

Suppose that

a

cows give

b

gallons of milk in

c

days. At this rate, how many gallons of milk will

d

cows give in

e

days?

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Solution

The rate is

\dfrac{b}{ac}

gallons per cow per day. So

d

cows over

e

days produce

\dfrac{b}{ac}\cdot d\cdot e=\dfrac{bde}{ac}

gallons. Thus, the correct answer is A.

Concepts: rate · ratio and proportion

Problem text and solution from the LIVE past-contest archive. See also the AoPS wiki page for community solutions.